If Itunes match fails to complete its scan process and is stuck in steps 1, 2 or 3 the following steps usually clears problems:
1. Hold option key (Mac) or shift key (PC) whilst turning of match. This clears genius/match cache.
2. Close iTunes. Optional - Reboot computer.
3. Open itunes and turn on match. Select "add this Computer" and see if process completes.
If you see the following when you go into the match screen and it has been likes this for a while, I suggest that you stop process and go to menu > store and select update Itunes match:
:
You should see this if you progess on from "Sending information" to "waiting for Apple.. This should happen within minutes:

You should also add icloud status column to song view - go to menu > view> view options and tick box. This will tell you what has been Matched, Uploaded, Purchased, Inelligible, Duplicate or Waiting.
Tracks that are "Waiting" may include one or more corrupt tracks. You may have to remove all "Waiting" tracks from your library as it is not always clear which ones are causing the problem. Large / Long tracks that will be uploaded may be the cause of the problem.
Once you have removed the tracks, follow steps 1 to 3 again and see if process completes. You can then readd the tracks, a small number at a time until all your music is added.
If problem persists, you should consider creating an alternative itunes library. http://support.apple.com/kb/ht1589.
This creates a new blank library. Turn on match and Select "add this Computer". Once process is complete you will see all the music that you have in match. If you see tracks with "waiting" Icloud status and are "greyed out", this may be the reason why the match process does not complete. Delete those tracks and go back to your original library. You may need to follow steps 1 to 3 above again.
Jim